FOCUS- It is already the majority in Denmark and could be more contagious. Studies are underway to investigate its transmissibility and severity.
For two days, the BA.2, a cousin strain of Omicron, worried. “We do not know its origin, its virulence, or its ability to escape immunity, including that conferred by Omicron. On the other hand, it seems to be more contagious“, explained Antoine Flahaut, epidemiologist and director of the Institute of global health at the University of Geneva, with our colleagues from LCI.
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Its name – BA.2 – corresponds to a nomenclature used by scientists to characterize the evolutions of Sars CoV2. In December, three genetic diversities are observed: BA.1; BA.2 and BA.3. “It has already become the majority in Denmark, a country that sequences strains a lot. In France, the sequencing is less. It is therefore difficult to know the real share of BA.2, but we will find out soon», continues Antoine Flahaut.
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Ongoing studies
After the Defense Council, Olivier Véran, the Minister of Health estimated that the BA.2 “don’t change the game“. “At this stage, there is no knowledge of the risk of contagiousness for those who have already contracted Omicron“, adding that the World Health Organization “did not classify it as a variant of interest, at least not at this stage. For what we know, it more or less matches the characteristics we know of Omicron“. The timetable for the lifting of restrictions is therefore maintained.
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During its press briefing, Santé Publique France indicated that “studies are underway to understand this phenomenon. There is no explanation at this point. Research will be carried out on its properties, and in particular on its transmissibility and its severity.“. The institution willclosely follow data from Denmark“.
According to Florence Débarre, researcher in evolutionary biology at the CNRS at Sorbonne University, contacted by Le Figaro, BA.2 stands for “to date, less than twenty sequences“. “A number to take with a grain of salt as sequencing can be slow. At this stage, there are no particular signals that would indicate a large circulation of BA.2 in France, but things may change“. According to the Outbreak site, which is based on Gisaid data, it would also be present in the United Kingdom, India, Sweden and Singapore.
No big difference with BA.1
“Very preliminary observations in India and Denmark suggest that there is no big difference in severity compared to BA.1. This data should solidify (one way or the other) in the coming weeks.“, reassures virologist Tom Peacock, from Imperial College London on Twitter.
A question arises: how to differentiate BA.1 and BA.2? “PCR detects the virus and identifies the Omicron. But it’s more complicated to know if it’s BA.1 and BA.2. Their identification depends on the laboratories“, notes Florence Débarre. Some kits used do not – yet – allow certain variations to be detected.